Referring to FIG. 1, a conventional recessed lamp (also known as “downlight”) structure 10 is shown as embedded in a ceiling 14 and includes a lamp holder 11 and a light bulb 12, wherein the lamp holder 11 has a bottom portion formed with an opening 111, and the light bulb 12 is installed in a receiving space 112 defined in the lamp holder 11. The bottom portion of the lamp holder 11 has a peripheral edge bent horizontally outward, thereby forming a circular annular frame 113 around the bottom portion of the lamp holder 11. In addition, the lamp holder 11 has a top portion formed with a sidewall, wherein the sidewall is symmetrically provided with two pivotal connectors 114, each connected with a torsion spring 13. Each torsion spring 13 has a first end passing through the corresponding pivot connector 114 and fixed to the inner side of the top portion of the lamp holder 11. Each torsion spring 13 further has a second end which, when no external force is applied thereto, is twisted away from the first end of the torsion spring 13 due to the stress of the torsion spring 13. Therefore, when it is desired to install the conventional recessed lamp structure 10 in a receiving hole 141 formed in the ceiling 14, the second end of each torsion spring 13 must be pushed toward the first end of the torsion spring 13 first. Then, the top portion of the lamp holder 11 is inserted into the receiving hole 141 of the ceiling 14. As soon as the push on the torsion springs 13 is released, the second ends of the torsion springs 13 are again twisted away from the corresponding first ends of the torsion springs 13 and press against a top side of the ceiling 14 due to the stress of the torsion springs 13, thereby providing the recessed lamp structure 10 with an upward supporting force. Thus, the recessed lamp structure 10 is positioned in the receiving hole 141 by the supporting force while the circular annular frame 113 covers the gap between the receiving hole 141 and the sidewall of the lamp holder 11.
Once the recessed lamp structure 10 is settled in the receiving hole 141, the second ends of the torsion springs 13 are twisted downward and press against the top side of the ceiling 14 due to the stress of the torsion springs 13. As a result, the ceiling 14 is clamped between the second ends of the torsion springs 13 and the circular annular frame 113. When it is desired to remove the recessed lamp structure 10 from the ceiling 14, the second ends of the torsion springs 13 must be pushed upward toward the corresponding first ends of the torsion springs 13, and the supporting force exerted on the recessed lamp structure 10 by the torsion springs 13 must be released, before the recessed lamp structure 10 can be pulled out of the receiving hole 141. However, as the torsion springs 13 are now shielded by the ceiling 14 and inaccessible to the user, the recessed lamp structure 10 cannot be efficiently removed. The user has to pull the portion of the recessed lamp structure 10 that is exposed outside the receiving hole 141 (i.e., the circular annular frame 113), thereby applying a downward force to the torsion springs 13. In response, the ceiling 14 applies a reaction force to the second ends of the torsion springs 13 and drives them upward. Thus, the supporting force acting on the recessed lamp structure 10 by the torsion springs 13 is removed, and the recessed lamp structure 10 is ready to be removed from the receiving hole 141. Nevertheless, the aforesaid operation tends to damage the overall structure of the receiving hole 141 of the ceiling 14 and hence produce a lot of wood chips and dust on the site. Moreover, immediately after the second ends of the torsion springs 13 leave the inner periphery of the receiving hole 141, the torsion springs 13 release the accumulated stress by twisting their second ends away from their first ends in a vigorous manner, and the vigorously twisting torsion springs 13 may pinch or even injure the user's fingers or palm. In short, the conventional recessed lamp structure 10 requires time-consuming and laborious installation and removal, tends to cause pinch injury to the user's fingers or palm during removal, and may result in irreparable damage to the receiving hole 141 formed in the ceiling 14. Consequently, it is prohibitively difficult to use the conventional recessed lamp structure 10 repeatedly in different places.
Referring to FIG. 2 for another conventional recessed lamp structure 60, the recessed lamp structure 60 includes a lamp holder 61, a fixing frame 62, and a light source element 63. The lamp holder 61 is laterally formed with a through hole 611 which allows the light source element 63 to be put into a receiving space 612 in the lamp holder 61 along a lateral direction. Additionally, the lamp holder 61 has a bottom portion with a peripheral edge bent horizontally outward such that a circular annular frame 613 is formed around the bottom portion of the lamp holder 61. The fixing frame 62 is fastened to a top portion of the lamp holder 61 by a screw 621. Besides, two bent engaging plates 64 are symmetrically provided at the two ends of the fixing frame 62. Each bent engaging plate 64 has two ends which are bent away from the lamp holder 61 and are symmetrically and protrudingly provided with a plurality of ribs 641. When it is desired to install the recessed lamp structure 60 in a receiving hole formed in a ceiling (not shown in the drawing but equivalent to the receiving hole 141 in the ceiling 14 as shown in FIG. 1), the top portion of the lamp holder 61 is directly inserted into the receiving hole of the ceiling such that the ribs 641 on the two ends of each bent engaging plate 64 engage with the inner periphery of the receiving hole. Thus, the recessed lamp structure 60 is positioned in the receiving hole by engagement between the bent engaging plates 64 and the receiving hole. Meanwhile, the gap between the receiving hole and the sidewall of the lamp holder 61 is covered by the circular annular frame 613.
However, a user trying to remove the recessed lamp structure 60 from the ceiling will face the same problem as with the recessed lamp structure 10 shown in FIG. 1. As the bent engaging plates 64 rely on the ribs 641 formed thereon to engage with the inner periphery of the receiving hole, the bent engaging plates 64 themselves are not very resilient, and the lack of resilience of the bent engaging plates 64 prevents efficient removal of the recessed lamp structure 60. Therefore, in order to remove the recessed lamp structure 60, the user must pull the portion of the recessed lamp structure 60 that is exposed outside the receiving hole (i.e., the circular annular frame 613), apply a downward force directly to the recessed lamp structure 60, and damage the inner periphery of the receiving hole so as to break the engagement between the bent engaging plates 64 and the inner periphery of the receiving hole. As a result, the receiving hole of the ceiling is structurally damaged and cannot be used to accommodate another recessed lamp. Besides, the foregoing operation also produces a huge amount of wood chips and dust that may inconvenience the user of the recessed lamp structure 60.
Furthermore, as the recessed lamp structure 60 is positioned in the receiving hole by engagement between the two bent ends of each bent engaging plate 64 and the inner periphery of the receiving hole, the shape of the circular annular frame 613 formed around the bottom portion of the recessed lamp structure 60 is limited by the configuration of the bent engaging plates 64 and must be circular. In other words, the circular annular frame 613 cannot be rectangular instead, or have a wavy perimeter, or take on other annular shapes. Now that the recessed lamp structure 60 can only be installed in a circular receiving hole but not a receiving hole of a rectangular or other shape, the field of application of the recessed lamp structure 60 is restricted.
Therefore, it has been an important subject in the related industry to develop a novel recessed lamp support structure that can overcome the aforementioned drawbacks of the conventional recessed lamp structures. It is desirable that the recessed lamp support structure can be securely positioned in a receiving hole by friction between the inner periphery of the receiving hole and a plurality of resilient plates that are provided on the recessed lamp support structure and configured to press tightly against the inner periphery of the receiving hole, thus enabling rapid and safe installation and removal of the recessed lamp support structure.